Cold Denaturation of the Molten Globule States of Apomyoglobin and a Profile for Protein Folding

Biochemistry ◽  
1994 ◽  
Vol 33 (16) ◽  
pp. 4903-4909 ◽  
Author(s):  
Ichiro Nishii ◽  
Mikio Kataoka ◽  
Fumio Tokunaga ◽  
Yuji Goto
Keyword(s):  
Protein Folding ◽  
Molten Globule ◽  
Cold Denaturation

Models of cooperativity in protein folding

1995 ◽  
Vol 348 (1323) ◽  
pp. 61-70 ◽  
Keyword(s):  
Protein Folding ◽  
Molten Globule ◽  
Core Collapse ◽  
Hydrophobic Core ◽  
Model Studies ◽  
Helix Formation ◽  
Collapse Model ◽  
Folding Pathways ◽  
State Behaviour ◽  
Denatured States

What is the basis for the two-state cooperativity of protein folding? Since the 1950s, three main models have been put forward. 1. In ‘helix-coil’ theory, cooperativity is due to local interactions among near neighbours in the sequence. Helix-coil cooperativity is probably not the principal basis for the folding of globular proteins because it is not two-state, the forces are weak, it does not account for sheet proteins, and there is no evidence that helix formation precedes the formation of a hydrophobic core in the folding pathways. 2. In the ‘sidechain packing’ model, cooperativity is attributed to the jigsaw-puzzle-like complementary fits of sidechains. This too is probably not the basis of folding cooperativity because exact models and experiments on homopolymers with sidechains give no evidence that sidechain freezing is two-state, sidechain complementarities in proteins are only weak trends, and the molten globule model predicted by this model is far more native-like than experiments indicate. 3. In the ‘hydrophobic core collapse’ model, cooperativity is due to the assembly of non-polar residues into a good core. Exact model studies show that this model gives two-state behaviour for some sequences of hydrophobic and polar monomers. It is based on strong forces. There is considerable experimental evidence for the kinetics this model predicts: the development of hydrophobic clusters and cores is concurrent with secondary structure formation. It predicts compact denatured states with sizes and degrees of disorder that are in reasonable agreement with experiments.

Molten globule intermediates and protein folding

1991 ◽  
Vol 19 (5) ◽  
Author(s):  
H. Christensen ◽  
R.H. Pain
Keyword(s):  
Protein Folding ◽  
Molten Globule

scholarly journals The molten globule intermediate of apomyoglobin and the process of protein folding

1993 ◽  
Vol 2 (6) ◽  
pp. 869-876 ◽  
Author(s):  
Doug Barrick ◽  
Robert L. Baldwin
Keyword(s):  
Protein Folding ◽  
Molten Globule

Kinetic and equilibrium folding intermediates

1995 ◽  
Vol 348 (1323) ◽  
pp. 35-41 ◽  
Keyword(s):  
Protein Folding ◽  
Molten Globule ◽  
Low Dielectric Constant ◽  
The Novel ◽  
Folding Intermediate ◽  
Molten Globule State ◽  
Folding Intermediates ◽  
First Order ◽  
Low Dielectric ◽  
First Order Phase

Our recent experiments on the molten globule state and other protein folding intermediates lead to following conclusions: (i) the molten globule is separated by intramolecular first-order phase transitions from the native and unfolded states and therefore is a specific thermodynamic state of protein molecules; (ii) the novel equilibrium folding intermediate (the ‘pre-molten globule’ state) exists which can be similar to the ‘burst’ kinetic intermediate of protein folding; (iii) proteins denature and release their non-polar ligands at moderately low pH and moderately low dielectric constant, i.e. under conditions which may be related to those near membranes.

High-Pressure NMR Studies of the Dissociation of Arc Represser and the Cold Denaturation of Ribonuclease A

1996 ◽  
Author(s):  
Xiangdong Peng ◽  
Jerson L. Silva
Keyword(s):  
High Pressure ◽  
High Resolution ◽  
Molten Globule ◽  
2D Nmr ◽  
Ribonuclease A ◽  
Nmr Studies ◽  
Cold Denaturation ◽  
Biochemical Systems ◽  
Nmr Techniques ◽  
Β Sheet

We begin this article with a brief discussion of the specialized high-resolution NMR instrumentation developed for high-pressure studies of biochemical systems. We then present the potential for the unique information content of high-pressure NMR spectroscopy as illustrated by the results of two NMR studies performed recently in our laboratory. Different denatured states of Arc represser are characterized by one-dimensional (1D) and two-dimensional (2D) NMR. Increasing pressure promotes sequential changes in the structure of Arc represser: from the native dimer through a predissociated state to a denaturated molten globule monomer. A compact state (molten globule) of Arc represser is obtained in the dissociation of Arc represser by pressure, whereas high temperature and urea induce dissociation and unfolding to less structured conformations. The presence of NOEs (Nuclear Overhauser Enhancement) in the β-sheet region in the dissociated state suggests that the intersubunit β-sheet (residues 6–14) in the native dimer is replaced by an intramonomer β-sheet. Changes in 2D NMR spectra prior to dissociation indicate the existence of a predissociated state that may represent an intermediate stage in the folding and subunit association pathway of Arc represser. The cold denaturation study of ribonuclease A has shown that high pressure can be utilized not only to perturb the protein structure in a controlled way but also to lower the freezing point of aqueous protein solutions substantially. As a result, one can access subzero temperatures and carry out cold denaturation studies of proteins. The results of the NMR study of the reversible cold denaturation are compared with the heat and pressure denaturation of bovine pancreatic ribonuclease A. High-resolution NMR spectra of complex molecules in the liquid phase usually exhibit a great deal of structure and yield a wealth of information about the molecule. Therefore, it is not surprising that multinuclear high-resolution Fourier transform NMR spectroscopy at high pressure represents the most promising technique in studies of the pressure effects on biochemical systems (Jonas & Jonas, 1994). The high information content of the various advanced NMR techniques, including 2D NMR techniques such as NOESY, COSY, and ROESY, have yet to be fully exploited in high-pressure NMR experiments.

scholarly journals Analysis of Protein Folding Equilibria by Nano-Electrospray-Ionization Mass Spectrometry

2002 ◽  
Vol 16 (3-4) ◽  
pp. 361-370 ◽  
Author(s):  
Irena Matecko ◽  
Norbert Müller ◽  
Rita Grandori
Keyword(s):  
Mass Spectrometry ◽  
Protein Folding ◽  
Electrospray Ionization ◽  
Electrospray Ionization Mass Spectrometry ◽  
Tertiary Structure ◽  
Molten Globule ◽  
Ionization Mass Spectrometry ◽  
Ionization Mass ◽  
Conformational States ◽  
Esi Ms

This paper summarizes recent findings from our group concerning applications of electrospray-ionization mass spectrometry (ESI-MS) to the study of protein folding. Nano-ESI-MS was employed for the investigation of protein conformational states under varying solvent conditions and at varying values of the instrumental parameters. The effect of trifluoroethanol (TFE) on a peptide and acid-unfolded cytochromec(cytc), monitored by circular dichroism (CD) and time-of-flight ESI-MS, illustrates the specificity of the latter technique for features of protein tertiary structure. Measurements on marginally stable protein states indicate that it is possible to identify operational conditions for nano-ESI-MS in which none of the instrumental parameters limits conformational stability in the protein sample. Results described here show that changes in the charge-state distributions (CSDs) under controlled conditions allow not only discriminating between native and denatured states, but also monitoring minor conformational changes, like the transition from molten globule to native state. These studies underscore the potential of mass spectrometry methods for the analysis of heterogeneous samples and, in particular, for the characterization of dynamic equilibria involving different conformational states.

scholarly journals Evidence for a molten globule state as a general intermediate in protein folding

FEBS Letters ◽  
1990 ◽  
Vol 262 (1) ◽  
pp. 20-24 ◽  
Author(s):  
O.B. Ptitsyn ◽  
R.H. Pain ◽  
G.V. Semisotnov ◽  
E. Zerovnik ◽  
O.I. Razgulyaev
Keyword(s):  
Protein Folding ◽  
Molten Globule ◽  
Molten Globule State
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